NASA's Mars Reconnaissance Rover spied these spider-like formations, likely caused as carbon dioxide ice changes from a solid to a gas; the gas moves through channels until it reaches the surface and vents out.

Spider-like formations, likely caused when carbon dioxide ice changes from a solid directly to a gas, appear throughout this image. As this process happens, gas moves through channels until it reaches the surface and vents out. These vents show up as the dark streaks because they carry dust and dirt up to the surface.

The High Resolution Imaging Science Experiment, which took this image, is the most powerful telescopic camera ever sent to another planet.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace & Technologies Corp., Boulder, Colo.

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